Lithium batteries have become the main energy storage device among all chemical power sources for use in portable electronic devices and electric power sources for electric or hybrid vehicles.
Recently, Lithium batteries having an iron phosphate based positive electrode have become the most promising type of lithium batteries for their safety factor and durability.
Lithium batteries exhibit a small initial internal resistance or impedance at the beginning of their life which must remain stable throughout the life of the battery. An increase of the internal resistance would have the effect, throughout the cycle life of the battery, of slowly reducing the battery performance until, after many cycles of charge and discharge, the battery capacity has faded to a level in which the battery no longer performs to the requirements of the application it powers. The higher the initial internal resistance is, the faster the battery capacity will fade and therefore the shorter the battery life will be.
Reducing the initial internal resistance or impedance of the battery would therefore increase the battery capacity at the beginning of its cycle life and also reduce the capacity fade of the battery throughout its cycle life thereby improving both the power delivery capacity of the battery and its longevity.
Therefore, there is a need for a lithium battery or cells having a lower internal resistance or impedance than other similar battery or cells and/or a method for lowering the impedance of the battery or cells.